Memory leak in the randomisation analyses

[GoogleCodeExporter]

The system consumes all the available memory over a series of iterations
(how fast depends on the size of the data set).  

Eventually it gets to the point that there is not enough memory to save the
data set or run any further analyses.  This occurs on WinXP, but is likely
to occur on all systems.

A workaround is to run the analysis for some number of iterations, save,
close and restart the application (this clears the memory), and then resume
the analysis.  Repeat solution as needed. 

The load_and_randomise_wrapper.pl script in the Biodiverse/bin folder has
been developed as a means of automating the close and restart problem but
will likely need modification for some problems.

Original issue reported on code.google.com by shawnlaffan on 25 Sep 2009 at 6:43